Piece of shit... 😞💩💩

So my 17 year old sister just moved in with me because she was living with our abusive mom. I told her I only had a few rules like curfew is 10:30 on school nights and 11:30 weekend nights unless she is having a sleep over. Those are only in place so that I know she is safe, but I said I could push till 12 or 12:30 as long as she texts me on weekend nights. I only ask that picks up her stuff in the living room and does her homework. I drive 30 minutes every morning to take her to school and let her hang out with friends till I am off work or till curfew. I am really lenient. I want her to be happy and comfortable especially with her brain tumor. I just went out and spent my entire paycheck (minus what I need for gas and my phone) and bought her brand new bedroom stuff so she had a nice comfy and cute room. Well, she is with my mom right now and I called to make sure she was ok and to make sure my mom wasn't hurting her and she didn't answer the phone the first time I called so got nervous and tried again, she answered and started yelling at me. She told me I am annoying and a piece of she for not leaving her alone. She said I need to lay off of her and stop trying to be her mother or she is going to hate me like she hates our mom. I am completely blown away. I haven't tried to be her mom at all. I just have small rules in place so she is safe and so I am not up all night worrying about her. My grandma and I even bought her her new phone because our mom broke her other one and I ask for is that she texts me to let me know she is alright. I am so hurt, I am just trying to be a good big sister, but I guess I'm going about it all wrong. IDK what to do... 💔😞